Journal of Academia and Industrial Research (JAIR)

Volume 2, Issue 6 November 2013 320

ISSN: 2278-5213

REVIEW ARTICLE

Surgical Face Masks: Manufacturing Methods and Classification

K.P. Chellamani*, D. Veerasubramanian and R.S. Vignesh Balaji

The South India Textile Research Association, Coimbatore, TN, India spg@sitra.org.in, kpc@sitra.org.in*; 0422-4215347______________________________________________________________________________________________ Abstract A surgical face mask is also known as a procedure mask and purposely to be worn by health care professionals during operation procedures. It helps to catch the bacteria shed in liquid droplets and aerosols from the wearer's mouth and nose. Normal activities such as sneezing, coughing, breathing and speaking may release oral, dermal and nasopharyngeal bacteria that may cause post-operative infections. Microorganisms have varying characteristics that can influence their potential ability to penetrate the facemask material including shape, size and their surface characteristics. Some studies reported that variety of pathogens are encountered in the hospital environment, a relatively limited number of hospital infections including Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Candida albicans and Staphylococcus aureus. Some studies reported that the rod shaped bacteria penetrate less than spherically shaped bacteria of similar size. This review focuses on surgical face masks and their classification based on the performance like filtration efficiency, pressure difference, splash resistance etc. Further, the quality evaluation of surgical face masks and standards for manufacturing surgical face masks has also been reviewed. Keywords: Surgical face mask, operation procedures, hospital infections, pathogens, filtration efficiency.

Introduction Hamilton also found that mouth is a source of

Healthcare workers involved in treating and caring for streptococcal bacteria which causes the communicableindividuals injured or sick as well as the patient can be diseases and recommended that physicians should wearexposed to biological aerosols capable of transmitting a specially constructed mouth guard. In 1918, weaverdiseases. These diseases, which may be caused by a published the results of his study on the surgical facevariety of microorganisms, can pose significant risks to masks which play a main role to spread of diphtheria,life and health (Chellamani and Thiruppathi, 2009). meningitis, pneumonia and so on. He introduced theSurgical face masks are used to cover the mouth and practice to cover the nose and mouth when caring thenose by doctors and other healthcare workers. It reduces patients (Hamilton, 1915).the risk of contaminations from secretion of the mouthand nose in operation room or clinics. It is purposely to Doust and lyon (1918) observed the role of surgical facebe worn by health care professionals during surgery and masks is to prevent the respiratory tract based infections.at same time to catch the bacteria shed in liquid droplets They also found that the surgical face masks with twoand aerosols from the wearer’s mouth and nose layers provide the better protection to the wearer as(Hayavadana and Vanitha, 2009). Surgical face masks compared to the single layer face masks. They alsowere originally developed to contain and filter droplets found that speaking with a surgical face masks in ancontaining microorganisms that are liberation from the ordinary conversation for 5 min release relatively fewmouth and nasopharynx of healthcare workers during bacteria from the mouth to a distance of only 1 tosurgery, thereby providing protection for the patient. 2 ft. In case of without surgical face masks, for 5 min, theHowever, there are several ways in which surgical face liberation of bacteria from the mouth is quite high. Andmasks contaminate the surgical wound. For example, the liberated bacteria are found even to as distance moredue to poor tying of surgical face masks and incorrectly than 3 ft (Belkin, 2009). Surgical face masks not onlyworn surgical face masks causes leaking of air from the provide a barrier for airborne organisms, it also protectsside of the surgical face mask (Hofmeyr et al., 2008). In the wearer against splashing of blood and other body1897, Mikulicz, a German physician, published the first fluids (Woodhead et al., 2002).study which supports the need for wearing a surgicalface masks. In 1906, Hamilton found that the Manufacturing methodstransmission of Infectious diseases and the importance The surgical face mask is produced using fabric formingof droplets of sputum in the dissemination of tuberculosis technology as shown in Fig. 1. They are a. Woven,infection. b. Non-woven and c. Knitted.

Fig. 1. Different fabric forming technology. The typical material used to manufacture surgical face masks are polypropylene with 20 gsm made using spunbond technology and 25 gsm polypropylene non-woven sheet made using meltblown technology. The surgical face masks are made in different sizes like 17.5 X 9.5 cm for adult, 14.5 X 9.5 cm for child use and 12 X 7 cm for infants. They are available in different color like white, blue, green, yellow and pink (Hayavadana and vanitha, 2009). Over the past decade, there has been a tremendous increase in the demand for polymeric nanofibres which are used in various applications including tissue engineering, protective clothing, filtration and sensors (Nayak et al., 2012). The nanofibers have a very large surface area to volume ratio, which makes a. Plain weave (Anon, 2010). them suitable to manufacture filtration products and particularly for medical textile products such as surgical facemasks, wound dressings, drug delivery systems etc. (Jayaraman et al., 2004).

Fibres used to manufacture surgical face masks

More effective surgical face masks which provides 85% or even 99% protection is required to prevent the spread of transmission diseases. The high degree of filtration efficiency is attained with a very fine filter layer of textile fibres covered on both sides with conventional non-woven bonded fabrics. The thickness of fibre is from <1 to 10 µm. Polypropylene, polystryrene, polycarbonate, polyethylene, polyester etc. are suitable for manufacturing surgical face masks. Apart from fibre selection, the filtration efficiency of surgical face masks depends on the method of manufacture, the structure of b. Non-woven (diytrade, 2013). web, the cross-sectional shape of the fibre and its change (McCarthy, 2011). The suitable polymers are converted as a non-woven sheet using spunbond technology or electrostatically produced web from solvents. The methods of electrostatically produced web have uniform web density giving a high degree of filtration efficiency and less web weight (Luneneschloss and Albrecht, 1985).

Benefits of non-woven based surgical face masks

Non-woven based surgical face masks are disposable. It is generally made up of three or four layers, often with two ﬁlters that filter the material, 1 µ in size. Hence, it traps bacteria of that size or larger. Face masks of this type can provide protection against bacteria for a minimum of 4 h (Lipp and Edwards, 2002). Advantages c. Knitted (stellas, 2013). of non-woven fabrics over woven fabric in filtration are higher air permeability, higher bacterial filtration efficiency, no yarn slippage and low manufacturing costEven though, there are three fabrics forming technology, (Kothari, 2008). The non-woven technology guaranteesnowadays, most of the surgical face masks are made up better barrier properties than cotton, polyester or evenof non-woven with a view of disposing after use. more advanced woven products. Besides, disposableNon-woven fabric forming technology is cheaper than non-wovens (surgical face masks, gowns, drape etc.) areother fabric forming technology like woven or knitted. sterilized, packaged, opened, used and then disposed.Most of the surgical face mask manufacturers produce Hence, there is a less risk of contamination after using ofthe surgical face mask using SMS (Spunbond Meltblown disposable non-wovens than reusable products eitherSpunbond) technology. woven or knitted.

In case of reusable non-woven, that should be Bacterial filtration efficiency in vitro (BFE): This testdecontaminated, washed, sterilized for every reuse. method is designed for measuring bacterial filtrationTable 1 shows that the superiority of disposable efficiency of surgical face masks using Staphylococcusnon-woven over other reusable products in terms of aureus as the challenge organism. Staphylococcusbarrier properties (Najjar et al., 2009). Disposable aureus is based on its clinical relevance as a leadingsurgical face masks are often perceived to have cause of nosocomial infections. A bacterial challengeprotective advantages over reusable surgical face aerosol is passed through the test specimen either facemasks; they must be immediately discarded as side or inner side at a flow rate of 28.3 L/min, allowingbio-hazardous materials. In contrast, reusable surgical evaluation of filtration efficiencies related to both patientface masks can be sterilized and laundered for reuse, generated aerosols and wearer generated aerosols.with a lifetime more than 50 cycles. However, reusable The mean particle size of the bacterial aerosol used insurgical face masks may be prescribed as less protective this test is maintained at 3.0±0.3 µm as per relevantand more time-consuming for production as well as ASTM specifications. A higher bacterial filtrationwashing and sterilization for reuse. The repeated efficiency percentage indicates the better protection levellaundering of reusable surgical face masks may for the patient and healthcare professionals againstconsume more energy and generate more waste water transmission diseases from the source of patient as wellto the environment (McCarthy, 2011). as healthcare professionals. Classifications of surgical face masks as per BFE in European standard EN 14683Classification of surgical face masks is as follows:As per international standard ASTM F 2100–07, surgical  BFE ≥ 95% indicates the Type-I surgical face masksface masks are generally classified in to 3 types. They  BFE ≥ 98% indicates the Type-II surgical face masks.are i) Low barrier, ii) Moderate barrier and iii) Highbarrier. The basic characteristics to distinguish the Breathing resistance (ΔP): Breathing resistance is usedsurgical face masks based on its barrier properties are to determine the resistance of airflow through thelisted in Table 2 (ASTM F 2100, 2007). facemask. The surgical face mask is subjected to controlled flow of air. The difference in airflow pressure ofQuality evaluation: European standards and ASTM inlet and outlet of the sample is measured.standards provides the standardize quality evaluation The difference in pressure is divided by the surface areaprocedure for surgical face masks to prevent (in cm2) of the sample. A lower in breathing resistancetransmission diseases from health care professionals to indicates a better comfort level to the end user (patientpatients and in certain situations vice-versa. Also provide and healthcare professionals). It means that breathing isthe critical requirements before marketing the surgical easier through the surgical face mask by wearer.face masks (EN 14683, 2005). There are five test During breathing, the surgical face mask will maintain itsmethods used to evaluate the performance of the shape in a better way.surgical face masks.

Classifications of surgical face masks based on  Consumer Product Safety Commission (CPSC) 16breathing resistance are as follows: CFR 1610: Standard for flammability of clothing For Type-I and II surgical face masks, the breathing textiles. resistance would be (non-splash resistant surgical  National Fire Production Agency (NFPA) Standard face masks) ≤3.0 mm H2O/cm2. 702-1980: Standard for classification of flammability For Type-IR and IIR surgical face masks, the of wearing apparel. breathing resistance would be (splash resistant  Underwriters Laboratory (UL) 2154: Fire test for surgical face masks) ≤ 5.0 mm H2O/cm2. surgical fabric.The increase in comfort of surgical face masks needs to The flame spread characteristics are classified in termshave a low breathing resistance value per cm2. For that, of class 1 to class 4 for the above tests. For NFPA,the available surface area of the facemask is increased class 1 indicates relatively slow burning where as CPSCand thereby the total area available for ventilation is standards, class 1 indicates that minimum of 3.5 sec orincreased. more required to ignite and spreading of flame on the specimen against the standard flame. In case of ULSplash resistance (ASTM F1862-07): Splash resistance standards, test to measure the quantity of atmosphericis used to determine the penetration resistance of oxygen required to propagate the flame while ignition issurgical face masks under high velocity stream of caused by an electro surgery unit or laser unit. Higherpotentially contaminated fixed volume of fluid (splash of levels of oxygen required for flame propagation indicatefluid) over a relatively short period of time. A specimen is that the materials are more flame resistant.supported on an apparatus that allows viewing the back FDA recommends that class 1 and class 2 flammabilityside of the specimen from behind. A fixed volume of materials are to be used to manufacture the surgical facesynthetic blood (stimulant fluid have equivalent liquid masks.characteristics like surface tension of actual blood andother body fluids), is aimed at the specimen and Conclusiondispersed at a known velocity. It simulates the impact of Disposable surgical face masks are worn by both patientblood or other body fluid onto the specimen. and healthcare professionals to reduce the frequency ofAny evidence of synthetic blood penetration on the back post-operative surgical wound infections. Theseside of the medical face mask constitutes failure. infections result to increase the medical expenses.Specimen medical face masks are evaluated at a total of Hence, the quality of the surgical face masks is essentialthree different velocities corresponding to human blood and the same is determined by standard testingpressures of 10.6, 16.0, and 21.3 kPa (80, 120 and procedure provide by internal standards like ASTM and160 mm Hg). Test results are reported at each velocity European standards. Reusable surgical face masks canand the medical face mask is rated at the highest be sterilized and laundered for reuse, with a lifetimecorresponding blood pressure. A higher splash more than 50 cycles. However, reusable surgical faceresistance means that the surgical face mask will protect masks have less filtration and protection efficiency asthe user in a better way against splashes of potentially compared to disposable one. As number of washingcontaminated fluid during a surgical procedure. cycle is increased the protection efficiency is decreasedClassifications of surgical face masks based on splash for reusable one. Also the repeated laundering ofresistance in European standard EN 14683 are as reusable surgical face masks may consume more energyfollows: and generate more waste water to the environment For Type-I and Type-II surgical face masks, this test is not applicable. Acknowledgements For Type-IR and Type-IIR surgical face masks, the Authors are thankful to Dr. Prakash Vasudevan, Director, specimen should be tested under the constant SITRA for his keen interest in this study. velocity of 120 mm Hg. ReferencesFlammability (16 CFR 1610): There are many potential 1. Anon. 2010. The American heritage dictionary of theignition sources in the operating room, including surgical English language, 4th edn. Published by Houghton Mifflinlasers, electrosurgical units, endoscopic fiber optics and Harcourt publishing company. Retrieved October 15,high-energy electro-medical devices. The materials used 2013, from http//images.yourdictionary.com/plain weave.in operation theatre will burn if high intensity heat energy 2. ASTM F 2100. 2007. Standard specification foris applied to them, especially in the presence of elevated performance of materials used in medical face masks,oxygen levels. Hence, the flammability test for surgical USA. pp.390-392.face masks is essential. The standards given below are 3. Belkin, N.L. 2009. The surgical mask has its firstused to determine the flammability by class for medical performance standarda century after it was introduced.device like surgical face masks (Guidance for Industry Bull. Amer. College Surgeons. 94(12): 22-25.and FDA staff, 2004).